From 19da0fe6f8a16ed9681d9bfea6986882d7800912 Mon Sep 17 00:00:00 2001
From: Renz <renz@uuxo.net>
Date: Fri, 14 Nov 2025 08:17:39 +0000
Subject: [PATCH] Add script to safely set max_locks_per_transaction and
 restart PostgreSQL

---
 fix_max_locks.sh | 49 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100755 fix_max_locks.sh

diff --git a/fix_max_locks.sh b/fix_max_locks.sh
new file mode 100755
index 0000000..5bf3c9e
--- /dev/null
+++ b/fix_max_locks.sh
@@ -0,0 +1,49 @@
+#!/usr/bin/env bash
+# fix_max_locks.sh
+# Safely update max_locks_per_transaction in postgresql.conf and restart PostgreSQL
+# Usage: sudo ./fix_max_locks.sh [NEW_VALUE]
+
+set -euo pipefail
+NEW_VALUE=${1:-256}
+
+CONFIG_FILE="$(sudo -u postgres psql -t -c "SHOW config_file;" | tr -d '[:space:]')"
+if [ -z "$CONFIG_FILE" ]; then
+  echo "Could not locate postgresql.conf; aborting"
+  exit 1
+fi
+
+echo "postgres config file: $CONFIG_FILE"
+BACKUP_FILE="${CONFIG_FILE}.bak.$(date +%s)"
+
+# Create a backup
+sudo cp "$CONFIG_FILE" "$BACKUP_FILE"
+sudo chown postgres:postgres "$BACKUP_FILE"
+chmod 600 "$BACKUP_FILE"
+
+echo "Backup written to $BACKUP_FILE"
+
+# Use sed to update (or add) setting
+# If the setting is present (commented or uncommented), replace the line. Otherwise append.
+if sudo grep -q "^\s*max_locks_per_transaction\s*=\s*" "$CONFIG_FILE"; then
+  echo "Updating existing max_locks_per_transaction to $NEW_VALUE"
+  sudo sed -ri "s#^\s*#?max_locks_per_transaction\s*=.*#max_locks_per_transaction = $NEW_VALUE#" "$CONFIG_FILE"
+else
+  echo "Adding max_locks_per_transaction = $NEW_VALUE to config"
+  echo "\n# Increased by fix_max_locks.sh on $(date)\nmax_locks_per_transaction = $NEW_VALUE" | sudo tee -a "$CONFIG_FILE" >/dev/null
+fi
+
+# Ensure correct permissions
+sudo chown postgres:postgres "$CONFIG_FILE"
+sudo chmod 600 "$CONFIG_FILE"
+
+# Restart PostgreSQL and verify
+echo "Restarting PostgreSQL service..."
+sudo systemctl restart postgresql
+sleep 2
+
+echo "Verifying new value:"
+sudo -u postgres psql -c "SHOW max_locks_per_transaction;"
+
+echo "If the restart fails, you can restore the previous config with:\n  sudo cp $BACKUP_FILE $CONFIG_FILE && sudo systemctl restart postgresql"
+
+exit 0